A wide variety of compositions are known in the art for providing cosmetic and/or pharmacologic benefits to human skin. Benefits sought include, for example, prevention, treatment or amelioration of environmental or age-related damage or deterioration of the skin, improved appearance by modifying surface characteristics, improved feel by moisturizing, and prevention or treatment of specific skin disorders. Many conventional cosmetic cream and lotion compositions are described, for example, in Sagarin, Cosmetics Science and Technology, 2nd Edition, Volume 1, Wiley lnterscience (1972), and Encyclopedia of Chemical Technology, Third Edition, Volume 7.
Starch derived from various plant sources has been commonly known in the art to provide a desirable skin feel in emulsions intended for topical use. While providing the desirable skin feel, the efficiency and performance of unmodified starch can be erratic. This had led to the development of various types of cross-linked and surface modified starches. One of these in wide use is modified with aluminum octenylsuccinate; an example brand of this is trademarked Dri-Flo by National Starch Inc. Although an improvement over unmodified starch, the material can cause excessive thickening of product when heated and the stability of some cold process emulsions (Pemulen systems) is compromised with use of this material.
Accordingly, there is a need for a topical formulation containing a modified starch that will impart desirable skin feel upon application to the skin, yet will also withstand the elevated temperatures during formulation and not cause excessive thickening of the resulting formulation.
In addition to the need for such a topical formulation, it would be advantageous to use these formulations as vehicles for both sunscreen and after sun formulations.
It is now generally recognized that exposure to solar radiation can have adverse health consequences, sometimes not appearing until several years following the exposure. Of course, the immediately appearing xe2x80x9csunburnxe2x80x9d from an overexposure can itself be a serious acute health problem.
Many products are available to reduce the amount of solar ultraviolet radiation received by the skin during exposure to the sun""s rays. Typical product formulations are lotions, creams, ointments or gels containing chemical and/or physical barriers to ultraviolet transmission. These vary considerably in their abilities to protect the skin against the physical and biochemical effects of ultraviolet radiation.
Earlier sunscreening formulations were designed to protect against sunburn from a limited solar exposure period, while transmitting sufficient radiation to permit skin tanning. However, the current focus is on eliminating as much ultraviolet exposure as possible, it being recognized that skin tanning, while esthetically pleasing to some, is a clear indication of tissue damage from overexposure to solar radiation. It has been recently discovered that any amount of unprotected exposure can potentially cause immune system suppression and lead to future health problems, such as skin carcinomas and other dermatological disorders.
The SPF (Sun Protection Factor) rating system has been developed to provide consumer guidance in selecting suitable sunscreens for any given outdoor activity. In general, the SPF number approximately corresponds to the multiple of time during which the properly applied sunscreen will prevent obvious reddening of the skin, over the exposure time that causes unprotected skin to exhibit reddening. Thus, a person should be able to remain in the sun without visible effects for eight times the usual unprotected duration, if an SPF 8 sunscreen formulation has been properly applied. Of course, the duration of unprotected exposure which produces a visible effect on the skin varies from one individual to another, due to differences in their skin cells. Currently popular are high-SPF xe2x80x9csunblockerxe2x80x9d products, having SPF values of at least 30.
One particular disadvantage of sunscreen products is developing a formulation containing sunscreen active agents that does not impart an oily feel when applied to the user""s skin. Accordingly, it would be advantageous to have a formulation containing sunscreen active agents that imparts an elegant feel upon application to the user""s skin. Similarly, non sunscreen emulsions can also have the disadvantage of an oily skin feel. Accordingly, it would also be advantageous to have a non sunscreen formulation that imparts an elegant feel upon application to the users skin, such as after sun and insect repellant formulations, either alone or in combination with a sunscreen active agent.
Accordingly the present invention provides an emulsion formulation for topical application to the skin comprising an aqueous phase, an oil phase, at least one emulsifier, and an epichlorohydrin cross-linked glyceryl starch.
The invention further provides an oil-in-water emulsion formulation for topical application to the skin comprising an aqueous phase, an oil phase, at least one emulsifier, and an epichlorohydrin cross-linked glyceryl starch.
The invention further provides a water-in-oil emulsion formulation for topical application to the skin comprising an aqueous phase, an oil phase, at least one emulsifier, and an epichlorohydrin cross-linked glyceryl starch.
The invention further provides an emulsion formulation for topical application to the skin comprising an aqueous phase, an oil phase, at least one emulsifier, an epichlorohydrin cross-linked glyceryl starch and at least one sunscreen active agent.
The invention further provides an oil-in-water emulsion formulation for topical application to the skin comprising an aqueous phase, an oil phase, at least one emulsifier, an epichlorohydrin cross-linked glyceryl starch and at least one sunscreen active agent.
The invention also provides an oil-in-water formulation for topical application to the skin comprising an aqueous phase, an oil phase, at least one emulsifier, an epichlorohydirn cross-linked glyceryl starch, and an insect repellant.
Finally, the invention further provides an oil-in-water formulation for topical application to the skin comprising an aqueous phase, an oil phase, at least one emulsifier, an epichlorohydrin cross-linked glyceryl starch, at least one sunscreen sunscreen active agent, and an insect repellant.